KA mount wierdness (ist DS and various KA mounts)

Hi everyone, first post!

I have a couple of P30s an ist DS and a bunch of K and KA mount lenses.

In particular I have 2 KA mount lenses that have an apparently identical mount.

One is a miranda 28mm and the other a "zeiss" japanese made 70-210 zoom. BUt I think the exact lenses is not whats at issue.

Both lenses fit and work fine on the P30s, and the miranda fits and works fine on the ist DS.

BUT the zeiss won't fit on the DS. It goes in and starts to turn but stops dead about halfway to where it should end up. I've had a look, and tried to mount the mount on the camera without the lens attached so i can peer inside , and I don't think its hanging up on the aperture lever (which sticks out the furthest) it may be hitting a flange on a spring in the camera mount, I can't see, but why?

Now - the mount really is identical to the miranda which fits fine, its not just that its KA - it looks like it was made by the same company from the same mould, and I can't see ANY difference between it and the one on the miranda.

so why would one fit and the other not? I'm completely bewildered!

Any suggestions please!

Hi, and welcome to the forum..

does the zeiss have a rear element that protrudes out from the back of the lens.. or more precisely, a metal ring with around a third of it's circumference raised? This is seen on some third party 70-210s (especially macro lenses) for some reason. I have a Soligor that does the same. Whatever you do, don't force it.. , but you do have the option of using a converter, or even macro tubes with it, so all's not lost.

Cheers

Liam

the zeiss rear element only protrudes if its zoomed right out, I've tried mounting it with the zoom in the middle and it makes no difference.

no metal ring with 1/3 raised circumference as far as I can see, I will try to post a photo in a little hwile

thanks for the response!

heres a couple of rough pics of the offending KA mount.

the inner element is zoomed out of the way.

http://www.tomdrinkwater.com/KAmnt1.jpg

http://www.tomdrinkwater.com/KAmnt2.jpg

I think the black plastic ring in the centre is the offender. Is this on the other mount? I think it is there to protect the aperture linkage. You can remove it, but it is still definitely worth checking it does not damage the camera.

most likely culprit:
one of the flanges on the mount, may be slightly bent.
A minor drop, or a little too much force could cause that.
It might not be visible to the naked eye, but even a fraction of a millimeter could explain your problem.

the black centre piece (metal not plastic AFAICT) is identical to the other mount, and is integral to the aperture lever, it can't be removed without removing the lever with it.

it might be worth trying removing it and see if the lens fits without it, since it would gain a clue as to where its sticking. I'll see if I can.

I suspect this may be right, i'll look for that.

If i could find a cheap /broken lens with the same mount and just swap the mounts that would solve it.

presumably the old P30s have more tolerance than the DS

YES!!!

thank-you Don!

it was one of the flanges bent slightly in, just barely visible, i bent it back and the lens fit on, with a little wiggling.

will bend it a tiny bit more to avoid the wiggling next time

I had a similar problem with a 28mm Kiron-made Vivitar. The little semi-circular collar shielding the rear element was the cause, but on that lens it was easily removed, seemingly without affecting the lens' functions. It didn't seem to do any harm, although I don't know how safe it is as it didn't get a lot of use on my k100d and I ended up replacing the collar-thingy for use on my P30.